kate snow, nbc news, china. >> provocative topic. kate snow will have more on this tonight as part of "rock center" at 10:00, 9:00 central here on nbc. we are back in a moment with a woman on a fast track to make history this weekend. track to history this weekend. with an irregular heartbeat.y the usual, bob? not today. [ male announcer ] bob has afib: atrial fibrillation not caused by a heart valve problem, a condition that puts him at greater risk for a stroke. [ gps ] turn left. i don't think so. [ male announcer ] for years, bob took warfarin, and made a monthly trip to the clinic to get his blood tested. but not anymore. bob's doctor recommended a different option: once-a-day xarelto®. xarelto® is the first and only once-a-day prescription blood thinner for patients with afib not caused by a heart valve problem, that doesn't require routine blood monitoring. like warfarin, xarelto® is proven effective to reduce the risk of an afib-related stroke. there is limited data on how these drugs compare when warfarin is well managed.